【公開日：2024.07.25】【最終更新日：2024.05.24】

課題データ / Project Data

課題番号 / Project Issue Number

23NM5446

利用課題名 / Title

Flexible Multicolor Security Display Sheets Coated with Metallosupramolecular Polymers for Electrochromic Printing and Natural Erasing by Humidity 

利用した実施機関 / Support Institute

物質・材料研究機構 / NIMS

機関外・機関内の利用 / External or Internal Use

内部利用（ARIM事業参画者以外）/Internal Use (by non ARIM members)

技術領域 / Technology Area

【横断技術領域 / Cross-Technology Area】（主 / Main）計測・分析/Advanced Characterization（副 / Sub）-

【重要技術領域 / Important Technology Area】（主 / Main）マテリアルの高度循環のための技術/Advanced materials recycling technologies（副 / Sub）-

キーワード / Keywords

X線光電子分光（XPS（硬X線を含む））/ X-ray photoelectron spectroscopy,有機エレクトロニクス/ Organic electronics,エレクトロクロミック素子,電子分光/ Electron spectroscopy,資源代替技術/ Resource alternative technology

利用者と利用形態 / User and Support Type

利用者名（課題申請者）/ User Name (Project Applicant)

樋口 昌芳

所属名 / Affiliation

物質・材料研究機構

共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes

JENA Satya Ranjan,ROY Susmita

ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes

安福 秀幸

利用形態 / Support Type

（主 / Main）技術補助/Technical Assistance（副 / Sub）-

利用した主な設備 / Equipment Used in This Project

NM-202：硬X線光電子分光分析装置（HAX-PES/XPS）

報告書データ / Report

概要（目的・用途・実施内容）/ Abstract (Aim, Use Applications and Contents)

In this study, we present an electrically color printing approach using electrochromic (EC) Fe(II) and Ru(II)-based metallosupramolecular polymers (MSPs), which were synthesized via complexation of the metal ions and a chelating terpyridine ligand. The printing method involves a flexible ITO film with a Fe(II)-based MSP layer (a polyFe EC film), an erasing unit, and a printing unit. To conduct the writing or erasing process, the erasing unit or the printing unit was stuck on the EC film and an oxidative or reductive potential was applied to the EC layer of the EC film. The printing and erasing of an image were caused by the oxidation state changes between Fe(II) and Fe(III) in the EC layer. Further, the change in the oxidation state was verified by comparing the binding energies of Fe before and after oxidation using the XPS technique.

実験 / Experimental

For XPS measurement, the homogeneous polyFe film was prepared on ITO (sheet resistance: 60 Ω/☐)-coated PET sheets by spin coating the polymer solutions in methanol. Finally, the obtained polymer layers were dried at room temperature. 

結果と考察 / Results and Discussion

We synthesized Fe(II)- and Ru(II)-based MSPs (polyFe and polyRu) using a 1:1 complexation method. The resulting polymers were soluble in polar solvents such as water and methanol. We prepared a thin layer of polyFe on an ITO-coated PET film (ITO-PET film) by spin-coating the solution. The erasing unit was prepared by pasting the electrolyte film on an ITO glass. The printing unit was prepared by pasting an insulating PVC sheet with hollowed-out figures, letters, or designs on the erasing unit. Electrochemical printing was successfully conducted by contacting the printing unit with the EC film and applying +3 V between the layers: The colorless figures/characters are displayed on the blue sheet because only the contacting part of the polyFe film with the electrolyte was electrochemically oxidized to change the color from blue to colorless. The printed characters were erased by placing the erasing unit on the printed EC paper and applying the opposite potential between the layers. In other words, the colorless state of the EC paper was obtained by electrochemical oxidation using the printing unit, and the colored state was obtained by applying the reduction potential between the paper and the erasing unit.  At +3.0 V, the MLCT absorption in the original polyFe film disappeared due to the oxidation of Fe(II) to Fe(III). The oxidation states of iron before and after the printing were confirmed by the XPS measurements. In the Fe(II) state before the oxidation, the binding energy of Fe2p_3/2 and Fe2p_1/2 appeared at 708.3 eV and 721.0 eV, respectively. On the other hand, after printing, the binding energies of Fe2p_3/2 and Fe2p_1/2 became larger (710.0 eV and 723.1 eV, respectively), because of the valence changes from Fe(II) to Fe(III). The difference in the binding energy of ~2 eV for Fe(II/III) state was also in accordance with the literature report.¹

図・表・数式 / Figures, Tables and Equations

Fig.1 The EC paper, after printing with the letter Z using the printing unit and the letter was erased using the erasing unit.

Fig.2 XPS binding energies of polyFe(II) and polyFe(III) film.

その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)

References   
1. Yamashita, T.; Hayes, P. Analysis of XPS Spectra of Fe²⁺ and Fe³⁺ Ions in Oxide Materials. Appl. Surf. Sci. 2008, 254, 2441–2449.

Acknowledgments
 This research work was financially supported by the Mirai project (grant number: JPMJMI21I4) from the Japan Science and Technology Agency (JST) and the Environment Research and Technology Development Fund (ERTDF) (JPMEERF20221M02) from Environmental Restoration and Conservation Agency (ERCA). We thank NIMS-ARIM shared facilities for XPS measurement.

成果発表・成果利用 / Publication and Patents

論文・プロシーディング（DOIのあるもの） / DOI (Publication and Proceedings)

1. Jian Zhang, Flexible Multicolor Rewritable Paper Coated with Metallosupramolecular Polymers for Electrochromic Printing and Natural Erasing by Humidity, ACS Applied Polymer Materials, 5, 6950-6957(2023).
   DOI: 10.1021/acsapm.3c00991
   

口頭発表、ポスター発表および、その他の論文 / Oral Presentations etc.

特許 / Patents

特許出願件数 / Number of Patent Applications：0件
特許登録件数 / Number of Registered Patents：0件